Many products are designed to receive electrical power from power adapters that accept a voltage from an available primary power source, such as, e.g., an AC utility line input or a 12V automobile electrical system, and provide a product-specific DC output voltage. Some power adapters may use a connector and a cable (e.g., a standard AC utility plug and a line cord) to connect the primary power source to the input of a power converter, and another cable and product-specific connector to connect the output of the power converter to the device to be powered. The power adapter may provide a regulated output voltage.
A plug apparatus for connecting to a standard AC utility socket, and which contains a battery charger within the plug apparatus, is described in Meinel et al, Hybrid Integrated Circuit Transformer, U.S. Pat. No. 5,353,001, issued Oct. 4, 1994. A plug apparatus for connecting to a standard AC utility socket, which contains a rectifier within the plug apparatus, is described in Lee, Power Adapter, U.S. Pat. No. 8,502,096, issued Aug. 6, 2013. A connector comprising a rectifier within the connector shell is described in Bernstein et al, Combined Connector and Rectifier, U.S. Pat. No. 3,484,864, issued Dec. 16, 1969.